Integrating chamber cone light using LED sources

ABSTRACT

A system to provide radiant energy of selectable spectral characteristic (e.g. a selectable color combination) uses an integrating cavity to combine energy of different wavelengths from different sources. The cavity has a diffusely reflective interior surface and an aperture for allowing emission of combined radiant energy. Sources of radiant energy of different wavelengths, typically different-color LEDs, supply radiant energy into the interior of the integrating cavity. In the examples, the points of entry of the energy into the cavity typically are located so that they are not directly visible through the aperture. The cavity effectively integrates the energy of different wavelengths, so that the combined radiant energy emitted through the aperture includes the radiant energy of the various wavelengths. The apparatus also includes a control circuit coupled to the sources for establishing output intensity of radiant energy of each of the sources. Control of the intensity of emission of the sources sets the amount of each wavelength of energy in the combined output and thus determines a spectral characteristic of the radiant energy output through the aperture.

TECHNICAL FIELD

The present subject matter relates to techniques and equipment toprovide radiant energy having a selectable spectral characteristic (e.g.a selectable color characteristic), by combining selected amounts ofradiant energy of different wavelengths from different sources, using anintegrating cavity.

BACKGROUND

An increasing variety of lighting applications require a preciselycontrolled spectral characteristic of the radiant energy. It has longbeen known that combining the light of one color with the light ofanother color creates a third color. For example, the commonly usedprimary colors Red, Green and Blue of different amounts can be combinedto produce almost any color in the visible spectrum. Adjustment of theamount of each primary color enables adjustment of the spectralproperties of the combined light stream. Recent developments forselectable color systems have utilized light emitting diodes as thesources of the different light colors.

Light emitting diodes (LEDs) were originally developed to providevisible indicators and information displays. For such luminanceapplications, the LEDs emitted relatively low power. However, in recentyears, improved LEDs have become available that produce relatively highintensities of output light. These higher power LEDs, for example, havebeen used in arrays for traffic lights. Today, LEDs are available inalmost any color in the color spectrum.

Systems are known which combine controlled amounts of projected lightfrom at least two LEDs of different primary colors. Attention isdirected, for example, to U.S. Pat. Nos. 6,459,919, 6,166,496 and6,150,774. Typically, such systems have relied on using pulse-widthmodulation or other modulation of the LED driver signals to adjust theintensity of each LED color output. The modulation requires complexcircuitry to implement. Also, such prior systems have relied on directradiation or illumination from the source LEDs. In some applications,the LEDs may represent undesirably bright sources if viewed directly.Also, the direct illumination from LEDs providing multiple colors oflight has not provided optimum combination throughout the field ofillumination.

Another problem arises from long-term use of LED type light sources. Asthe LEDs age, the output intensity for a given input level of the LEDdrive current decreases. As a result, it may be necessary to increasepower to an LED to maintain a desired output level. This increases powerconsumption. In some cases, the circuitry may not be able to provideenough light to maintain the desired light output level. As performanceof the LEDs of different colors declines differently with age (e.g. dueto differences in usage), it may be difficult to maintain desiredrelative output levels and therefore difficult to maintain the desiredspectral characteristics of the combined output. The output levels ofLEDs also vary with actual temperature (thermal) that may be caused bydifferences in ambient conditions or different operational heatingand/or cooling of different LEDs. Temperature induced changes inperformance cause changes in the spectrum of light output.

U.S. Pat. No. 6,007,225 to Ramer et al. (Assigned to Advanced OpticalTechnologies, L.L.C.) discloses a directed lighting system utilizing aconical light deflector. At least a portion of the interior surface ofthe conical deflector has a specular reflectivity. In several disclosedembodiments, the source is coupled to an optical integrating cavity; andan outlet aperture is coupled to the narrow end of the conical lightdeflector. This patented lighting system provides relative uniform lightintensity and efficient distribution of light over a field ofillumination defined by the angle and distal edge of the deflector.However, this patent does not discuss particular color combinations oreffects.

Hence, a need still exists for a technique to efficiently combine energyfrom multiple sources having multiple wavelengths and direct the radiantenergy effectively toward a desired field of illumination. A relatedneed still exists for such a system that does not require complexelectronics (e.g. modulation circuitry) to control the intensity of theenergy output from the sources of the radiant energy of differentwavelengths. A need also exists for a technique to effectively maintaina desired energy output level and the desired spectral character of thecombined output as LED performance decreases with age, preferablywithout requiring excessive power levels.

SUMMARY

As disclosed herein, an apparatus for emitting radiant energy includesan integrating cavity, having a diffusely reflective interior surfaceand an aperture for allowing emission of integrated radiant energy.Sources supply radiant energy into the interior of the integratingcavity. At least two of the sources emit radiant energy of differentwavelengths. The cavity effectively combines the energy of differentwavelengths, so that the radiant energy emitted through the apertureincludes the radiant energy of the various wavelengths. The apparatusalso includes a control circuit coupled to the sources for establishingoutput intensity of radiant energy of each of the sources. Control ofthe intensity of emission of the sources sets a spectral characteristicof the combined radiant energy emitted through the aperture.

In the examples, the points of entry of the energy from the sources intothe cavity are located so that the emission points are not directlyvisible through the aperture. Each source typically comprises one ormore light emitting diodes (LEDs). It is possible to install anydesirable number of LEDs. Hence, In several examples, the sources maycomprise one or more LEDs for emitting light of a first color, and oneor more LEDs for emitting light of a second color, wherein the secondcolor is different from the first color. In a similar fashion, theapparatus may include additional LED sources of a third color, a fourthcolor, etc. To achieve the highest color-rendering index (CRI), the LEDarray may include LEDs of colors that effectively cover the entirevisible spectrum.

These sources can include any color or wavelength, but typically includered, green, and blue. The integrating or mixing capability of thechamber serves to project light of any color, including white light, byadjusting the intensity of the various sources coupled to the cavity.Hence, it is possible to control color rendering index, as well as colortemperature. The system works with the totality of light output from afamily of LEDs. However, to provide color adjustment or variability, itis not necessary to control the output of individual LEDs, except as theintensity of each contributes to the totality. For example, it is notnecessary to modulate the LED outputs. Also, the distribution pattern ofthe LEDs is not significant. The LEDs can be arranged in any manner tosupply radiant energy within the chamber, although typically direct viewfrom outside the fixture is avoided.

The LED sources may be coupled to openings at the points on the interiorof the cavity, to emit radiant energy directly into the interior of theintegrating cavity. It is also envisioned that the sources may besomewhat separated from the cavity, in which case, the device mightinclude optical fibers coupled between the sources and the integratingcavity, to supply radiant energy from the sources to the emission pointsinto the interior of the cavity.

In the disclosed examples, the apparatus further comprises a conicaldeflector. A small opening at a proximal end of the deflector is coupledto the aperture of the integrating cavity. The deflector has a largeropening at a distal end thereof. The deflector comprises a reflectiveinterior surface between the distal end and the proximal end. In theexamples, at least a substantial portion of the reflective interiorsurface of the conical deflector exhibits specular reflectivity withrespect to the combined radiant energy. The conical deflector defines anangular field of radiant energy emission from the apparatus.

An exemplary system includes a number of “sleeper” LEDs that would beactivated only when needed, for example, to maintain the light output,color, color temperature or thermal temperature. Hence, examples arealso disclosed in which the first color LEDs comprise one or moreinitially active LEDs for emitting light of the first color and one ormore initially inactive LEDs for emitting light of the first color on anas needed basis. Similarly, the second color LEDs include one or moreinitially active LEDs for emitting light of the second color and one ormore initially inactive LEDs for emitting light of the second color onan as needed basis. In a similar fashion, the apparatus may includeadditional active and inactive LED sources of a third color, fourthcolor, etc.

As noted in the background, as LEDs age or experience increases inthermal temperature, they continue to operate, but at a reduced outputlevel. The use of the sleeper LEDs greatly extends the lifecycle of thefixtures. Activating a sleeper (previously inactive) LED, for example,provides compensation for the decrease in output of the originallyactive LED. There is also more flexibility in the range of intensitiesthat the fixtures may provide.

A number of different examples of control circuits are discussed below.In one example, the control circuitry comprises a color sensor coupledto detect color distribution in the combined radiant energy. Associatedlogic circuitry, responsive to the detected color distribution, controlsthe output intensity of the various LEDs, so as to provide a desiredcolor distribution in the integrated radiant energy. In an example usingsleeper LEDs, the logic circuitry is responsive to the detected colordistribution to selectively activate the inactive light emitting diodesas needed, to maintain the desired color distribution in the combinedradiant energy.

A number of other control circuit features also are disclosed. Forexample, the control circuitry may also include a temperature sensor. Insuch an example, the logic circuitry is also responsive to the sensedtemperature, e.g. to reduce intensity of the source outputs tocompensate for temperature increases.

The control circuitry may include an appropriate device for manuallysetting the desired spectral characteristic, for example, one or morevariable resistors or one or more dip switches, to allow a user todefine or select the desired color distribution.

Automatic controls also are envisioned. For example, the controlcircuitry may include a data interface coupled to the logic circuitry,for receiving data defining the desired color distribution. Such aninterface would allow input of control data from a separate or evenremote device, such as a personal computer, personal digital assistantor the like. A number of the devices, with such data interfaces, may becontrolled from a common central location or device.

The control may be somewhat static, e.g. set the desired color referenceindex or desired color temperature and the overall intensity and leavethe device set-up in that manner for an indefinite period. The apparatusalso may be controlled dynamically, for example, to vary the color ofthe combined light output and thereby provide special effects lighting.Where a number of the devices are arranged in a large two-dimensionalarray, dynamic control of color and intensity of each unit could evenprovide a video display capability, for example, for use as a“Jumbo-Tron” view screen in a stadium or the like.

The disclosed apparatus may use a variety of different structures orarrangements for the integrating cavity. It is desirable that theinterior cavity surface have a highly efficient diffusely reflectivecharacteristic, e.g. a reflectivity of over 90%, with respect to therelevant wavelengths, in order to maximize optical efficiency. Inseveral examples, the cavity is formed of a diffusely reflective plasticmaterial, such as a polypropylene having a 98% reflectivity and adiffuse reflective characteristic. Another example of a material with asuitable reflectivity is SPECTRALON. Alternatively, the integratingcavity may comprise a rigid substrate having an interior surface, and adiffusely reflective coating layer formed on the interior surface of thesubstrate so as to provide the diffusely reflective interior surface ofthe integrating cavity.

A variety of different shapes may be used for the interior reflectivesurface of the cavity. Although it may be rectangular, triangular or inthe shape of a pyramid, in the examples, the diffusely reflectiveinterior surface of the integrating cavity has a shape corresponding toa substantial portion of a sphere (e.g. hemispherical) or a substantialportion of a cylinder (e.g. approximating a half-cylinder).

To provide a uniform output distribution from the apparatus, it is alsopossible to construct the cavity so as to provide constructiveocclusion. Constructive Occlusion type transducer systems utilize anelectrical/optical transducer optically coupled to an active area of thesystem, typically the aperture of a cavity or an effective apertureformed by a reflection of the cavity. The systems utilize diffuselyreflective surfaces, such that the active area exhibits a substantiallyLambertian characteristic. A mask occludes a portion of the active areaof the system, in the examples, the aperture of the cavity or theeffective aperture formed by the cavity reflection, in such a manner asto achieve a desired response or output characteristic for the system.In examples of the present apparatus using constructive occlusion, theintegrating cavity would include a base, a mask and a cavity formed inthe base or the mask. The mask would have a diffusely reflectivesurface. The mask is sized and positioned relative to the active area ofthe system so as to constructively occlude the active area.

In one example of the present apparatus using constructive occlusive,the device would further include a mask outside the integrating cavityformed in the base. The mask would have a diffusely reflective surfacefacing toward the aperture of the cavity. The mask is sized andpositioned relative to the aperture so as to constructively occlude theaperture. In another constructive occlusion example, the aperture thatserves as the active area is actually a reflection of the interiorsurface of a dome that forms the curved interior of the cavity. Thereflection is formed on a base surface opposite the cavity of the dome.The interior of the cavity is diffusely reflective. In this laterarrangement, the dome also serves as the constructive occlusion mask.

The inventive devices have numerous applications, and the outputintensity and spectral characteristic may be tailored and/or adjusted tosuit the particular application. For example, the intensity of theintegrated radiant energy emitted through the aperture may be at a levelfor use in a lumination application or at a level sufficient for a tasklighting application.

Additional objects, advantages and novel features of the examples willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing and the accompanying drawings or may be learned by productionor operation of the examples. The objects and advantages of the presentsubject matter may be realized and attained by means of themethodologies, instrumentalities and combinations particularly pointedout in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accord withthe present concepts, by way of example only, not by way of limitations.In the figures, like reference numerals refer to the same or similarelements.

FIG. 1 illustrates an example of a radiant energy emitting system, withcertain elements thereof shown in cross-section.

FIG. 2A is an exploded side-view of the components of a fixture usableas the cavity, deflector and sources, in the system of FIG. 1.

FIG. 2B is an exploded view of the components of FIG. 2A, with thosecomponents shown in cross-section.

FIG. 2C is an end view of the deflector.

FIG. 2D is an end view of the cavity assembly.

FIG. 2E is a plan view of the LED support ring.

FIG. 3 illustrates another example of a radiant energy emitting system,with certain elements thereof shown in cross-section.

FIG. 4 is a bottom view of the fixture in the system of FIG. 3.

FIG. 5 illustrates another example of a radiant energy emitting system,using fiber optic links from the LEDs to the integrating cavity.

FIG. 6 illustrates another example of a radiant energy emitting system,utilizing principles of constructive occlusion.

FIG. 7 is a bottom view of the fixture in the system of FIG. 6.

FIG. 8 illustrates an alternate example of a radiant energy emittingsystem, utilizing principles of constructive occlusion.

FIG. 9 is a top plan view of the fixture in the system of FIG. 8.

FIG. 10 is a functional block diagram of the electrical components, ofone of the radiant energy emitting systems, using programmable digitalcontrol logic.

FIG. 11 is a circuit diagram showing the electrical components, of oneof the radiant energy emitting systems, using analog control circuitry.

FIG. 12 is a diagram, illustrating a number of radiant energy emittingsystem with common control from a master control unit.

FIG. 13 is a layout diagram, useful in explaining an arrangement of anumber of the fixtures of the system of FIG. 12.

FIG. 14 depicts the emission openings of a number of the fixtures,arranged in a two-dimensional array.

DETAILED DESCRIPTION

Reference now is made in detail to the examples illustrated in theaccompanying drawings and discussed below. FIG. 1 is a cross-sectionalillustration of a radiant energy distribution apparatus or system 10.For task lighting applications, the apparatus emits light in the visiblespectrum, although the device 10 may be used for lumination applicationsand/or with emissions in or extending into the infrared and/orultraviolet portions of the radiant energy spectrum.

The illustrated apparatus 10 includes an integrating cavity 11 having adiffusely reflective interior surface. The cavity 11 may have variousshapes. The illustrated cross-section would be substantially the same ifthe cavity is hemispherical or if the cavity is semi-cylindrical withthe cross-section taken perpendicular to the longitudinal axis.

The disclosed apparatus may use a variety of different structures orarrangements for the integrating cavity, examples of which are discussedbelow relative to FIGS. 3–9. It is desirable that the cavity surfacehave a highly efficient diffusely reflective characteristic, e.g. areflectivity of over 90%, with respect to the relevant wavelengths. Inthe example, the surface is highly diffusely reflective to energy in thevisible, near-infrared, and ultraviolet wavelengths.

The cavity may be formed of a diffusely reflective plastic material,such as a polypropylene having a 98% reflectivity and a diffusereflective characteristic. Such a highly reflective polypropylene isavailable from Ferro Corporation—Specialty Plastics Group, Filled andReinforced Plastics Division, in Evansville, Ind. Another example of amaterial with a suitable reflectivity is SPECTRALON. Alternatively, theintegrating cavity may comprise a rigid substrate having an interiorsurface, and a diffusely reflective coating layer formed on the interiorsurface of the substrate so as to provide the diffusely reflectiveinterior surface of the integrating cavity. The coating layer, forexample, might take the form of a flat-white paint. A suitable paintmight include a zinc-oxide based pigment, consisting essentially of anuncalcined zinc oxide and preferably containing a small amount of adispersing agent. The pigment is mixed with an alkali metal silicatevehicle-binder, which preferably is a potassium silicate, to form thecoating material. For more information regarding the paint, attention isdirected to U.S. patent application Ser. No. 09/866,516, which was filedMay 29, 2001, by Matthew Brown.

For purposes of the discussion, the cavity 11 in the apparatus 10 isassumed to be hemispherical. In the example, a hemispherical dome 13 anda substantially flat cover plate 15 form the cavity 11. At least theinterior facing surfaces of the dome 13 and the cover plate 15 arehighly diffusely reflective, so that the resulting integrating cavity 11is highly diffusely reflective with respect to the radiant energyspectrum produced by the device 10. Although shown as separate elements,the dome and plate may be formed as an integral unit.

The integrating cavity 11 has an aperture 17 for allowing emission ofcombined radiant energy. In the example, the aperture 17 is a passagethrough the approximate center of the cover plate 15. Because of thediffuse reflectivity within the cavity 11, light within the cavity isintegrated before passage out of the aperture 17. In the examples, theapparatus 10 is shown emitting the combined radiant energy downwardthrough the aperture 17, for convenience. However, the apparatus 10 maybe oriented in any desired direction to perform a desired applicationfunction, for example to provide visible luminance to persons in aparticular direction or location with respect to the fixture or toilluminate a different surface such as a wall, floor or table top.

The apparatus 10 also includes sources of radiant energy of differentwavelengths. In the example, the sources are LEDs 19, two of which arevisible in the illustrated cross-section. The LEDs 19 supply radiantenergy into the interior of the integrating cavity 11. As shown, thepoints of emission into the interior of the integrating cavity are notdirectly visible through the aperture 17. At least the two illustratedLEDs emit radiant energy of different wavelengths. Additional LEDs ofthe same or different colors may be provided. The cavity 11 effectivelyintegrates the energy of different wavelengths, so that the integratedor combined radiant energy emitted through the aperture 17 includes theradiant energy of all the various wavelengths in relative amountssubstantially corresponding to the relative intensities of input intothe cavity.

The source LEDs 19 can include LEDs of any color or wavelength.Typically, an array of LEDs for a visible light application includes atleast red, green, and blue LEDs. The integrating or mixing capability ofthe cavity 11 serves to project light of any color, including whitelight, by adjusting the intensity of the various sources coupled to thecavity. Hence, it is possible to control color rendering index (CRI), aswell as color temperature. The system works with the totality of lightoutput from a family of LEDs 19. However, to provide color adjustment orvariability, it is not necessary to control the output of individualLEDs, except as they contribute to the totality. For example, it is notnecessary to modulate the LED outputs. Also, the distribution pattern ofthe individual LEDs and their emission points into the cavity are notsignificant. The LEDs 19 can be arranged in any manner to supply radiantenergy within the chamber, so long as direct view from outside thefixture is avoided.

In this example, light outputs of the LED sources 19 are coupleddirectly to openings at points on the interior of the cavity 11, to emitradiant energy directly into the interior of the integrating cavity. TheLEDs may be located to emit light at points on the interior wall of theelement 13, though preferably such points would still be in regions outof the direct line of sight through the aperture 17. For ease ofconstruction, however, the openings for the LEDs 19 are formed throughthe cover plate 15. On the plate, the openings/LEDs may be at anyconvenient locations.

The apparatus 10 also includes a control circuit 21 coupled to the LEDs19 for establishing output intensity of radiant energy of each of theLED sources. The control circuit 21 typically includes a power supplycircuit coupled to a source, shown as an AC power source 23. The controlcircuit 21 also includes an appropriate number of LED driver circuitsfor controlling the power applied to each of the individual LEDs 19 andthus the intensity of radiant energy supplied to the cavity 11 for eachdifferent wavelength. Control of the intensity of emission of thesources sets a spectral characteristic of the combined radiant energyemitted through the aperture of the integrating cavity. The controlcircuit 21 may be responsive to a number of different control inputsignals, for example, in response to one or more user inputs as shown bythe arrow in FIG. 1. Although not shown in this simple example, feedbackmay also be provided. Specific examples of the control circuitry arediscussed in more detail later.

The color integrating energy distribution apparatus may also utilize oneor more conical deflectors having a specular reflective inner surface,to efficiently direct most of the light emerging from a light sourceinto a relatively narrow field of view. Hence, the exemplary apparatusshown in FIG. 1 also comprises a conical deflector 25. A small openingat a proximal end of the deflector is coupled to the aperture 17 of theintegrating cavity 11. The deflector 25 has a larger opening 27 at adistal end thereof. The angle and distal opening of the conicaldeflector 25 define an angular field of radiant energy emission from theapparatus 10. Although not shown, the large opening of the deflector maybe covered with a transparent plate or lens, or covered with a grating,to prevent entry of dirt or debris through the cone into the system.

The conical deflector may have a variety of different shapes, dependingon the particular lighting application. In the example, where cavity 11is hemispherical, the cross-section of the conical deflector istypically circular. However, the deflector may be somewhat oval inshape. In applications using a semi-cylindrical cavity, the deflectormay be elongated or even rectangular in cross-section. The shape of theaperture 17 also may vary, but will typically match the shape of thesmall end opening of the deflector 25. Hence, in the example, theaperture 17 would be circular. However, for a device with asemi-cylindrical cavity and a deflector with a rectangularcross-section, the aperture may be rectangular.

The deflector 25 comprises a reflective interior surface 29 between thedistal end and the proximal end. In the examples, at least a substantialportion of the reflective interior surface 29 of the conical deflectorexhibits specular reflectivity with respect to the integrated radiantenergy. As discussed in U.S. Pat. No. 6,007,225, for some applications,it may be desirable to construct the deflector 25 so that at least someportion(s) of the inner surface 29 exhibit diffuse reflectivity orexhibit a different degree of specular reflectivity (e.g.,-quasi-specular), so as to tailor the performance of the deflector 25 tothe particular application.

In the examples, each source of radiant energy of a particularwavelength comprises one or more light emitting diodes (LEDs). Withinthe chamber, it is possible to process light received from any desirablenumber of LEDs. Hence, in several examples, the sources may comprise oneor more LEDs for emitting light of a first color, and one or more LEDsfor emitting light of a second color, wherein the second color isdifferent from the first color. In a similar fashion, the apparatus mayinclude additional sources comprising one or more LEDs of a third color,a fourth color, etc. To achieve the highest color rendering index (CRI),the LED array may include LEDs of various wavelengths that covervirtually the entire visible spectrum.

FIGS. 2A to 2E are detail views of the light fixture components of anexample of a system of the type described above relative to FIG. 1. FIG.2A is an exploded side-view of the set 200 of the fixture components,and FIG. 2B is a similar view but showing some of those components incross-section. As shown, the fixture elements 200 include twoquarter-spherical domes 201 and 203 that are joined to form theintegrating cavity and a portion of an LED mounting structure. The domes201 and 203 are formed of a rigid material having a highly diffuselyreflective inner surface, as discussed above.

Each dome includes a boss 205 or 207 near the back apex thereof. Whenthe domes 201 and 203 are joined to form the cavity, the bosses 205 and207 together form a ring-shaped back shoulder that can be used formounting the fixture.

The illustrated components also include twelve LEDs 209 (six of whichare visible in FIGS. 2A and 2B). The LEDs 209 provide differentwavelengths of light as discussed earlier. In one example, the deviceincludes six Red LEDs, three Green LEDs and three Blue LEDs.

FIG. 2D is an end view of the cavity assembly, that is to say, showingthe two domes 201 and 203 joined together. As shown in cross-section inFIG. 2B, each dome includes an inwardly extending half-circular shoulder211 or 213. When the domes are joined as in FIG. 2D, these shoulders211, 213 together form a ring-shaped cover of the cavity. Thering-shaped cover provides one half of a sandwich like structure, forsupporting the LEDs 209. The central opening 215 of the cover forms theaperture of the integrating cavity. Openings 221 through the cover allowpassage of light from the LEDs 209 into the interior of the cavity.

The shoulders 211 and 213 include two half-circular bosses aroundrespective portions of the inner opening 215. When the two halves of thecavity structure are joined (FIG. 2D), these bosses form two innerflanges 217 and 219, extending toward the direction of intendedillumination. The groove formed between the flanges 217 and 219 receivesthe distal end of the conical deflector 223. FIG. 2C is an end view ofthe deflector 223. In the example, the entire inner surface 225 of thedeflector 223 has a specular reflective characteristic.

As discussed and shown, the cavity assembly includes shoulders 211 and213, which together form the cover of the cavity and form half of theLED support structure. The LEDs 209 are attached to the back (upwardside in FIGS. 2A and 2B) of an LED support ring 227, which provides theother half of the LED support structure. The LED support ring 227 may bemade of a suitable rigid material, which is resistant to the heatgenerated by the LEDs. For example, the LED support ring 227 may beconstructed of aluminum, to provide the necessary structural support andto act as a heat sink to wick away a substantial portion of the heatgenerated by the attached LEDs 209. Although not shown, ventilation orother cooling elements may also be provided.

In this example, for each LED 209, there are six small mounting holes229 through the LED support ring 227 (see FIG. 2E). The LED support ring227 also has six outwardly extending ‘tabs’ 231 around its perimeter, tofacilitate mounting. Although not shown for convenience, the cavityassembly (FIG. 2D) has three small bosses/tabs around the outside thatmate to three of the six tabs 231 on the LED support ring 227.

The central passage 233 of the LED support ring 227 is somewhat largerin diameter than the proximal (small) end of the conical deflector 223.During assembly, the proximal end of the conical deflector 223 passesthrough the opening 233 and mates in the groove formed between thegroove formed between the flanges 217 and 219. In this way, the proximalend of the deflector surrounds the aperture 215. Those skilled in theart will recognize that the structure of FIGS. 2A to 2E is exemplary andother structures may be used, for example, to mount desired numbers ofLEDs and/or to couple/attach the deflector to the aperture.

FIGS. 3 and 4 illustrate another example of a radiant energydistribution apparatus or system. FIG. 3 shows the overall system 30,including the fixture and the control circuitry. The fixture is shown incross-section. FIG. 4 is a bottom view of the fixture. The system 30 isgenerally similar the system 10. For example, the system 30 may utilizeessentially the same type of control circuit 21 and power source 23, asin the earlier example. However, the shape of the integrating cavity andthe deflector are somewhat different.

The integrating cavity 31 has a diffusely reflective interior surface.In this example, the cavity 31 has a shape corresponding to asubstantial portion of a cylinder. In the cross-sectional view of FIG. 3(taken across the longitudinal axis of the cavity), the cavity 31appears to have an almost circular shape. In this example, the cavity 31is formed by a cylindrical element 33. At least the interior surface ofthe element 33 is highly diffusely reflective, so that the resultingintegrating cavity 31 is highly diffusely reflective with respect to theradiant energy spectrum produced by the device 30.

The integrating cavity 31 has an aperture 35 for allowing emission ofcombined radiant energy. In this example, the aperture 35 is arectangular passage through the wall of the cylindrical element 33.Because of the diffuse reflectivity within the cavity 31, light withinthe cavity is integrated before passage out of the aperture 35.

The apparatus 30 also includes sources of radiant energy of differentwavelengths. In this example, the sources comprise LEDs 37, 39. The LEDsare mounted in openings through the wall of the cylindrical element 33,to essentially form two rows of LEDs on opposite sides of the aperture35. The positions of these openings, and thus the positions of the LEDs37 and 39, typically are such that the LED outputs are not directlyvisible through the aperture 35, otherwise the locations are a matter ofarbitrary choice.

Thus, the LEDs 37 and 39 supply radiant energy into the interior of theintegrating cavity 31, through openings at points on the interiorsurface of the integrating cavity not directly visible through theaperture 35. A number of the LEDs emit radiant energy of differentwavelengths. For example, arbitrary pairs of the LEDs 37, 39 might emitfour different colors of light, e.g. Red, Green, Blue and a fourth colorchosen to provide an increased variability of the spectralcharacteristic of the integrated radiant energy.

Alternatively, a number of the LEDs may be initially active LEDs,whereas others are initially inactive sleeper LEDs. For example, theinitially active LEDs might include two Red LEDs, two Green LEDs and aBlue LED; and the sleeper LEDs might include one Red LED, one Green LEDand one Blue LED.

The control circuit 21 controls the power provided to each of the LEDs37 and 39. The cavity 31 effectively integrates the energy of differentwavelengths, from the various LEDs 37 and 39, so that the integratedradiant energy emitted through the aperture 35 includes the radiantenergy of all the various wavelengths. Control of the intensity ofemission of the sources, by the control circuit 21, sets a spectralcharacteristic of the integrated radiant energy emitted through theaperture 35. If sleeper LEDs are provided, the control also activatesone or more dormant LEDs, when extra output of a particular wavelengthor color is required.

The color integrating energy distribution apparatus 30 may also includea deflector 41 having a specular reflective inner surface 43, toefficiently direct most of the light emerging from the aperture into arelatively narrow field of view. The deflector 41 expands outward from asmall end thereof coupled to the aperture 35. The deflector 41 has alarger opening 45 at a distal end thereof. The angle of the side wallsof the deflector and the shape of the distal opening 45 of the deflector41 define an angular field of radiant energy emission from the apparatus30.

As noted above, the deflector may have a variety of different shapes,depending on the particular lighting application. In the example, wherethe cavity 31 is substantially cylindrical, and the aperture isrectangular, the cross-section of the deflector 41 (viewed across thelongitudinal axis as in FIG. 3) typically appears conical, since thedeflector expands outward as it extends away from the aperture 35.However, when viewed on-end (bottom view—FIG. 4), the openings aresubstantially rectangular, although they may have somewhat roundedcorners. Alternatively, the deflector 41 may be somewhat oval in shape.The shapes of the cavity and the aperture may vary, for example, to haverounded ends, and the deflector may be contoured to match the aperture.

The deflector 41 comprises a reflective interior surface 43 between thedistal end and the proximal end. In the examples, at least a substantialportion of the reflective interior surface 43 of the conical deflectorexhibits specular reflectivity with respect to the combined radiantenergy, although regions exhibiting a different reflectivity may beprovided, as noted in the discussion of FIG. 1.

If provided, “sleeper” LEDs would be activated only when needed tomaintain the light output, color, color temperature, and/or thermaltemperature. As discussed later with regard to an exemplary controlcircuit, the system 30 could have a color sensor coupled to providefeedback to the control circuit 21. The sensor could be within thecavity or the deflector or at an outside point illuminated by theintegrated light from the fixture.

As LEDs age, they continue to operate, but at a reduced output level.The use of the sleeper LEDs greatly extends the lifecycle of thefixtures. Activating a sleeper (previously inactive) LED, for example,provides compensation for the decrease in output of the originallyactive LED. There is also more flexibility in the range of intensitiesthat the fixtures may provide.

In the examples discussed above relative to FIG. 1 to 4, the LED sourceswere coupled directly to openings at the points on the interior of thecavity, to emit radiant energy directly into the interior of theintegrating cavity. It is also envisioned that the sources may besomewhat separated from the cavity, in which case, the device mightinclude optical fibers or other forms of light guides coupled betweenthe sources and the integrating cavity, to supply radiant energy fromthe sources to the emission points into the interior of the cavity. FIG.5 depicts such a system 50, which uses optical fibers.

The system 50 includes an integrating cavity 51, an aperture 53 and adeflector with a reflective interior surface 55, similar to those in theearlier embodiments. The interior surface of the integrating cavity 51is highly diffusely reflective, whereas the deflector surface 55exhibits a specular reflectivity.

The system 50 includes a control circuit 21 and power source 23, as inthe earlier embodiments. In the system 50, the radiant energy sourcescomprises LEDs 59 of three different wavelengths, e.g. to provide Red,Green and Blue light respectively. The sources may also include one ormore additional LEDs 61, either of a different color or for use as‘sleepers,’ similar to the example of FIGS. 3 and 4. In this example(FIG. 5), the cover plate 63 of the cavity 51 has openings into whichare fitted the light emitting distal ends of optical fibers 65. Theproximal light receiving ends of the fibers 65 are coupled to receivelight emitted by the LEDs 59 (and 61 if provided). In this way, the LEDsources 59, 61 may be separate from the chamber 51, for example, toallow easier and more effective dissipation of heat from the LEDs. Thefibers 65 transport the light from the LED sources 59, 61 to the cavity51. The cavity 51 integrates the different colors of light from the LEDsas in the earlier examples and supplies combined light out through theaperture 53. The deflector, in turn, directs the combined light to adesired field. Again, the intensity control by the circuit 21 adjuststhe amount or intensity of the light of each wavelength provided by theLED sources and thus controls the spectral characteristic of thecombined light output.

A number of different examples of control circuits are discussed below.In one example, the control circuitry comprises a color sensor coupledto detect color distribution in the integrated radiant energy.Associated logic circuitry, responsive to the detected colordistribution, controls the output intensity of the various LEDs, so asto provide a desired color distribution in the integrated radiantenergy. In an example using sleeper LEDs, the logic circuitry isresponsive to the detected color distribution to selectively activatethe inactive light emitting diodes as needed, to maintain the desiredcolor distribution in the integrated radiant energy.

To provide a uniform output distribution from the apparatus, it is alsopossible to construct the cavity so as to provide constructiveocclusion. Constructive Occlusion type transducer systems utilize anelectrical/optical transducer optically coupled to an active area of thesystem, typically the aperture of a cavity or an effective apertureformed by a reflection of the cavity. The systems utilize diffuselyreflective surfaces, such that the active area exhibits a substantiallyLambertian characteristic. A mask occludes a portion of the active areaof the system, in the examples, the aperture of the cavity or theeffective aperture formed by the cavity reflection, in such a manner asto achieve a desired response or output performance characteristic forthe system. In examples of the present apparatus using constructiveocclusion, the integrating cavity comprises a base, a mask and a cavityin either the base or the mask. The mask would have a diffuselyreflective surface facing toward the aperture. The mask is sized andpositioned relative to the active area so as to constructively occludethe active area. It may be helpful to consider two examples usingconstructive occlusion.

FIGS. 6 and 7 depict a first, simple embodiment of a light distributorapparatus or system 70, for projecting integrated multi-wavelength lightwith a tailored intensity distribution, using the principles ofconstructive occlusion. In the cross-section illustration, the system 70is oriented to provide downward illumination. Such a system might bemounted in or suspended from a ceiling or canopy or the like. Thoseskilled in the art will recognize that the designer may choose to orientthe system 70 in different directions, to adapt the system to otherlighting applications.

The lighting system 70 includes a base 73, having or forming a cavity75, and adjacent shoulders 77 and 79, constructed in a manner similar tothe elements forming integrating cavities in the earlier examples. Inparticular, the interior of the cavity 75 is diffusely reflective, andthe down-facing surfaces of shoulders 77 and 79 may be reflective. Ifthe shoulder surfaces are reflective, they may be specular or diffuselyreflective. A mask 81 is disposed between the cavity aperture 85 and thefield to be illuminated. In this symmetrical embodiment, the interiorwall of a half-cylindrical base 73 forms the cavity; therefore theaperture 85 is rectangular. The shoulders 77 formed along the sides ofthe aperture 85 are rectangular. If the base were circular, with ahemispherical cavity, the shoulders typically would form a ring that maycompletely surround the aperture.

In many constructive occlusion embodiments, the cavity 75 comprises asubstantial segment of a sphere. For example, the cavity may besubstantially hemispherical, as in earlier examples. However, thecavity's shape is not of critical importance. A variety of other shapesmay be used. In the illustrated example, the half-cylindrical cavity 75has a rectangular aperture, and if extended longitudinally, therectangular aperture may approach a nearly linear aperture (slit).Practically any cavity shape is effective, so long as it has a diffusereflective inner surface. A hemisphere or the illustrated half-cylindershape are preferred for the ease in modeling for the light output towardthe field of intended illumination and the attendant ease ofmanufacture. Also, sharp corners tend to trap some reflected energy andreduce output efficiency.

For purposes of constructive occlusion, the base 73 may be considered tohave an active optical area, preferably exhibiting a substantiallyLambertian energy distribution. Where the cavity is formed in the base,for example, the planar aperture 85 formed by the rim or perimeter ofthe cavity 75 forms the active surface with substantially Lambertiandistribution of energy emerging through the aperture. As shown in alater embodiment, the cavity may be formed in the facing surface of themask. In such a system, the surface of the base may be a diffuselyreflective surface, therefore the active area on the base wouldessentially be the mirror image of the cavity aperture on the basesurface, that is to say the area reflecting energy emerging from thephysical aperture of the cavity in the mask.

The mask 81 constructively occludes a portion of the optically activearea of the base with respect to the field of intended illumination. Inthe example of FIG. 6, the optically active area is the aperture 85 ofthe cavity 75; therefore the mask 81 occludes a substantial portion ofthe aperture 85, including the portion of the aperture on and about theaxis of the mask and cavity system.

The relative dimensions of the mask 81 and aperture 85, for example therelative widths (or diameters or radii in a more circular system) aswell as the distance of the mask 81 away from the aperture 85, controlthe constructive occlusion performance characteristics of the lightingsystem 70. Certain combinations of these parameters produce a relativelyuniform emission intensity with respect to angles of emission, over awide portion of the field of view about the system axis (verticallydownward in FIG. 6), covered principally by the constructive occlusion.Other combinations of size and height result in a system performancethat is uniform with respect to a wide planar surface perpendicular tothe system axis at a fixed distance from the active area.

The shoulders 77, 79 also are reflective and therefore deflect at leastsome light downward. The angles of the shoulders and the reflectivity ofthe surfaces thereof facing toward the region to be illuminated byconstructive occlusion also contribute to the intensity distributionover that region. In the illustrated example, the reflective shouldersare horizontal, although they may be angled somewhat downward from theplane of the aperture.

With respect to the energy of different wavelengths, the interior spaceformed between the cavity 75 and the facing surface of the mask 81operates as an integrating cavity, in essentially the same manner as theintegrating cavities in the previous embodiments. Again, the LEDsprovide light of a number of different colors, and thus of differentwavelengths. The integrating cavity combines the light of multiple colorsupplied from the LEDs 87. The control circuit 21 controls the amount ofeach color of light supplied to the chamber and thus the proportionthereof included in the combined output light. The constructiveocclusion serves to distribute that light in a desired manner over afield or area that the system 70 is intended to illuminate.

The LEDs could be located at (or coupled by optical fiber to emit light)from any location or part of the surface of the cavity 75. Preferably,the LED outputs are not directly visible through the un-occludedportions of the aperture 85 (between the mask and the edge of thecavity). In examples of the type shown in FIGS. 6 and 7, the easiest wayto so position the LED outputs is to mount the LEDs 87 (or providefibers or the like) so as to supply light to the chamber throughopenings through the mask 81.

FIG. 7 also provides an example of an arrangement of the LEDs in whichthere are both active and inactive (sleeper) LEDs of the various colors.As shown, the active part of the array of LEDs 87 includes two Red LEDs(R), one Green LED (G) and one Blue LED (B). The initially inactive partof the array of LEDs 87 include one Red sleeper LEDs (RS), one Greensleeper LED (GS) and one Blue sleeper LED (BS). If other wavelengths aredesired, the apparatus may include an active LED of the other color (O)as well as a sleeper LED of the other color (OS). The precise number,type, arrangement and mounting technique of the LEDs and the associatedports through the mask 81 are not critical. The number of LEDs, forexample, is chosen to provide a desired level of output energy(intensity), for a given application.

The system 70 includes a control circuit 21 and power source 23. Theseelements control the operation and output intensity of each LED 87. Theindividual intensities determine the amount of each color light includedin the integrated and distributed output. The control circuit 21functions in essentially the same manner as in the other examples.

FIGS. 8 and 9 illustrate a second constructive occlusion example. Inthis example, the physical cavity is actually formed in the mask, andthe active area of the base is a flat reflective panel of the base.

The illustrated system 90 comprises a flat base panel 91, a mask 93, LEDlight sources 95, and a conical deflector 97. The system 90 iscircularly symmetrical about a vertical axis, although it could berectangular or have other shapes. The base 91 includes a flat centralregion 99 between the walls of the deflector 97. The region 99 isreflective and forms or contains the active optical area on the basefacing toward the region or area to be illuminated by the system 90.

The mask 93 is positioned between the base 91 and the region to beilluminated by constructive occlusion. For example, in the orientationshown, the mask 93 is above the active optical area 99 of the base 91,for example to direct light toward a ceiling for indirect illumination.Of course, the mask and cavity system could be inverted to serve as adownlight for task lighting applications, or the mask and cavity systemcould be oriented to emit light in directions appropriate for otherapplications.

In this example, the mask 93 contains the diffusely reflective cavity101, constructed in a manner similar to the integrating cavities in theearlier examples. The physical aperture 103 of the cavity 101 and of anydiffusely reflective surface(s) of the mask 93 that may surround thataperture form the active optical area on the mask 93. Such an activearea on the mask faces away from the region to be illuminated and towardthe active surface 99 on the base 91. The surface 99 is reflective,preferably with a diffuse characteristic. The surface 99 of the base 91essentially acts to produce a diffused mirror image of the mask 93 withits cavity 101 as projected onto the base area 99. The reflection formedby the active area of the base becomes the effective aperture of thelight integrating cavity (between the mask and base) when the fixture isconsidered from the perspective of the area of intended illumination.The surface area 99 reflects energy emerging from the aperture 103 ofthe cavity 101 in the mask 93. The mask 93 in turn constructivelyoccludes light diffused from the active base surface 99 with respect tothe region illuminated by the system 90. The dimensions and relativepositions of the mask and active region on the base control theperformance of the system, in essentially the same manner as in the maskand cavity system of FIGS. 6 and 7.

The system 90 includes a control circuit 21 and associated power source23, for supplying controlled electrical power to the LED sources 95. Inthis example, the LEDs emit light through openings through the base 91,preferably at points not directly visible from outside the system. TheLEDs 95 supply various wavelengths of light, and the circuit 21 controlsthe power of each LED, to control the amount of each color of light inthe combined output, as discussed above relative to the other examples.

The base 91 could have a flat ring-shaped shoulder with a reflectivesurface. In this example, however, the shoulder is angled toward thedesired field of illumination to form a conical deflector 97. The innersurface of the deflector 97 is reflective, as in the earlier examples.

The deflector 97 has the shape of a truncated cone, in this example,with a circular lateral cross section. The cone has two circularopenings. The cone tapers from the large end opening to the narrow endopening, which is coupled to the active area 99 of the base 91. Thenarrow end of the deflector cone receives light from the surface 99 andthus from diffuse reflections between the base and the mask.

The entire area of the inner surface of the cone 97 is reflective. Atleast a portion of the reflective surface is specular, as in thedeflectors of the earlier examples. The angle of the wall(s) of theconical deflector 97 substantially corresponds to the angle of thedesired field of view of the illumination intended for the system 90.Because of the reflectivity of the wall of the cone 97, most if not allof the light reflected by the inner surface thereof would at leastachieve an angle that keeps the light within the field of view.

The LED light sources 95 emit multiple wavelengths of light into themask cavity 101. The light sources 95 may direct some light toward theinner surface of the deflector 97. Light rays impacting on the diffuselyreflective surfaces, particularly those on the inner surface of thecavity 101 and the facing surface 99 of the base 91, reflect and diffuseone or more times within the confines of the system and emerge throughthe gap between the perimeter of the active area 99 of the base and theouter edge of the mask 93. The mask cavity 101 and the base surface 99function as an integrating cavity with respect to the light of variouswavelengths. The light emitted through the gap and/or reflected from thesurface of the inner surface of the deflector 97 irradiates a region(upward in the illustrated orientation) with a desired intensitydistribution and with a desired spectral characteristic, essentially asin the earlier examples.

Additional information regarding constructive occlusion based systemsfor generating and distributing radiant energy may be found in commonlyassigned U.S. Pat. Nos. 6,342,695, 6,334,700, 6,286,979, 6,266,136 and6,238,077. The color integration principles discussed herein may beadapted to any of the constructive occlusion devices discussed in thosepatents.

The inventive devices have numerous applications, and the outputintensity and spectral characteristic may be tailored and/or adjusted tosuit the particular application. For example, the intensity of theintegrated radiant energy emitted through the aperture may be at a levelfor use in a rumination application or at a level sufficient for a tasklighting application. A number of other control circuit features alsomay be implemented. For example, the control may maintain a set colorcharacteristic in response to feedback from a color sensor. The controlcircuitry may also include a temperature sensor. In such an example, thelogic circuitry is also responsive to the sensed temperature, e.g. toreduce intensity of the source outputs to compensate for temperatureincreases. The control circuitry may include an appropriate device formanually setting the desired spectral characteristic, for example, oneor more variable resistors or one or more dip switches, to allow a userto define or select the desired color distribution.

Automatic controls also are envisioned. For example, the controlcircuitry may include a data interface coupled to the logic circuitry,for receiving data defining the desired color distribution. Such aninterface would allow input of control data from a separate or evenremote device, such as a personal computer, personal digital assistantor the like. A number of the devices, with such data interfaces, may becontrolled from a common central location or device.

The control may be somewhat static, e.g. set the desired color referenceindex or desired color temperature and the overall intensity, and leavethe device set-up in that manner for an indefinite period. The apparatusalso may be controlled dynamically, for example, to provide specialeffects lighting. Where a number of the devices are arranged in a largetwo-dimensional array, dynamic control of color and intensity of eachunit could even provide a video display capability, for example, for useas a “Jumbo-Tron” view screen in a stadium or the like.

To appreciate the features and examples of the control circuitryoutlined above, it may be helpful to consider specific examples withreference to appropriate diagrams.

FIG. 10 is a block diagram of exemplary circuitry for the sources andassociated control circuit, providing digital programmable control,which may be utilized with a light integrating fixture of the typedescribed above. In this circuit example, the sources of radiant energyof the various wavelengths takes the form of an LED array 111. The array111 comprises two or more LEDs of each of the three primary colors, red,green and blue, represented by LED blocks 113, 115 and 117. For example,the array may comprise six red LEDs 113, three green LEDs 115 and threeblue LEDs 117.

The LED array in this example also includes a number of additional or“other” LEDs 119. There are two types of additional LEDs that are ofparticular interest in the present discussion. One type of additionalLED provides one or more additional wavelengths of radiant energy forintegration within the chamber. The additional wavelengths may be in thevisible portion of the light spectrum, to allow a greater degree ofcolor adjustment. Alternatively, the additional wavelength LEDs mayprovide energy in one or more wavelengths outside the visible spectrum,for example, in the infrared range or the ultraviolet range.

The second type of additional LED that may be included in the system isa sleeper LED. As discussed above, some LEDs would be active, whereasthe sleepers would be inactive, at least during initial operation. Usingthe circuitry of FIG. 10 as an example, the Red LEDs 113, Green LEDs 115and Blue LEDs 117 might normally be active. The LEDs 119 would besleeper LEDs, typically including one or more LEDs of each color used inthe particular system.

The electrical components shown in FIG. 10 also include an LED controlsystem 120. The system 120 includes driver circuits for the various LEDsand a microcontroller. The driver circuits supply electrical current tothe respective LEDs 113 to 119 to cause the LEDs to emit light. Thedriver circuit 121 drives the Red LEDs 113, the driver circuit 123drives the green LEDs 115, and the driver circuit 125 drives the BlueLEDs 117. In a similar fashion, when active, the driver circuit 127provides electrical current to the other LEDs 119. If the other LEDsprovide another color of light, and are connected in series, there maybe a single driver circuit 127. If the LEDs are sleepers, it may bedesirable to provide a separate driver circuit 127 for each of the LEDs119. The intensity of the emitted light of a given LED is proportionalto the level of current supplied by the respective driver circuit.

The current output of each driver circuit is controlled by the higherlevel logic of the system. In this digital control example, that logicis implemented by a programmable microcontroller 129, although thoseskilled in the art will recognize that the logic could take other forms,such as discrete logic components, an application specific integratedcircuit (ASIC), etc.

The LED driver circuits and the microcontroller 129 receive power from apower supply 131, which is connected to an appropriate power source (notseparately shown). For most task-lighting applications, the power sourcewill be an AC line current source, however, some applications mayutilize DC power from a battery or the like. The power supply 129converts the voltage and current from the source to the levels needed bythe driver circuits 121–127 and the microcontroller 129.

A programmable microcontroller typically includes or has coupled theretorandom-access memory (RAM) for storing data and read-only memory (ROM)and/or electrically erasable read only memory (EEROM) for storingcontrol programming and any pre-defined operational parameters, such aspre-established light ‘recipes.’ The microcontroller 129 itselfcomprises registers and other components for implementing a centralprocessing unit (CPU) and possibly an associated arithmetic logic unit.The CPU implements the program to process data in the desired manner andthereby generate desired control outputs.

The microcontroller 129 is programmed to control the LED driver circuits121–127 to set the individual output intensities of the LEDs to desiredlevels, so that the combined light emitted from the aperture of thecavity has a desired spectral characteristic and a desired overallintensity. The microcontroller 129 may be programmed to essentiallyestablish and maintain a desired ‘recipe’ or mixture of the availablewavelengths provided by the LEDs used in the particular system. Themicrocontroller 129 receives control inputs specifying the particular‘recipe’ or mixture, as will be discussed below. To insure that thedesired mixture is maintained, the microcontroller receives a colorfeedback signal from an appropriate color sensor. The microcontrollermay also be responsive to a feedback signal from a temperature sensor,for example, in or near the integrating cavity.

The electrical system will also include one or more control inputs 133for inputting information instructing the microcontroller 129 as to thedesired operational settings. A number of different types of inputs maybe used and several alternatives are illustrated for convenience. Agiven installation may include a selected one or more of the illustratedcontrol input mechanisms.

As one example, user inputs may take the form of a number ofpotentiometers 135. The number would typically correspond to the numberof different light wavelengths provided by the particular LED array 111.The potentiometers 135 typically connect through one or more analog todigital conversion interfaces provided by the microcontroller 129 (or inassociated circuitry). To set the parameters for the integrated lightoutput, the user adjusts the potentiometers 135 to set the intensity foreach color. The microcontroller 129 senses the input settings andcontrols the LED driver circuits accordingly, to set correspondingintensity levels for the LEDs providing the light of the variouswavelengths.

Another user input implementation might utilize one or more dip switches137. For example, there might be a series of such switches to input acode corresponding to one of a number of recipes. The memory used by themicrocontroller 129 would store the necessary intensity levels for thedifferent color LEDs in the array 111 for each recipe. Based on theinput code, the microcontroller 129 retrieves the appropriate recipefrom memory. Then, the microcontroller 129 controls the LED drivercircuits 121–127 accordingly, to set corresponding intensity levels forthe LEDs 113–119 providing the light of the various wavelengths.

As an alternative or in addition to the user input in the form ofpotentiometers 135 or dip switches 137, the microcontroller 129 may beresponsive to control data supplied from a separate source or a remotesource. For that purpose, some versions of the system will include oneor more communication interfaces. One example of a general class of suchinterfaces is a wired interface 139. One type of wired interfacetypically enables communications to and/or from a personal computer orthe like, typically within the premises in which the fixture operates.Examples of such local wired interfaces include USB, RS-232, andwire-type local area network (LAN) interfaces. Other wired interfaces,such as appropriate modems, might enable cable or telephone linecommunications with a remote computer, typically outside the premises.Other examples of data interfaces provide wireless communications, asrepresented by the interface 141 in the drawing. Wireless interfaces,for example, use radio frequency (RF) or infrared (IR) links. Thewireless communications may be local on-premises communications,analogous to a wireless local area network (WLAN). Alternatively, thewireless communications may enable communication with a remote deviceoutside the premises, using wireless links to a wide area network.

As noted above, the electrical components may also include one or morefeedback sensors 143, to provide system performance measurements asfeedback signals to the control logic, implemented in this example bythe microcontroller 129. A variety of different sensors may be used,alone or in combination, for different applications. In the illustratedexamples, the set 143 of feedback sensors includes a color sensor 145and a temperature sensor 147. Although not shown, other sensors, such asan overall intensity sensor may be used. The sensors are positioned inor around the system to measure the appropriate physical condition, e.g.temperature, color, intensity, etc.

The color sensor 145, for example, is coupled to detect colordistribution in the integrated radiant energy. The color sensor may becoupled to sense energy within the integrating cavity, within thedeflector (if provided) or at a point in the field illuminated by theparticular system. Various examples of appropriate color sensors areknown. For example, the color sensor may be a digital compatible sensor,of the type sold by TAOS, Inc. Another suitable sensor might use thequadrant light detector disclosed in U.S. Pat. No. 5,877,490, withappropriate color separation on the various light detector elements (seeU.S. Pat. No. 5,914,487 for discussion of the color analysis).

The associated logic circuitry, responsive to the detected colordistribution, controls the output intensity of the various LEDs, so asto provide a desired color distribution in the integrated radiantenergy, in accord with appropriate settings. In an example using sleeperLEDs, the logic circuitry is responsive to the detected colordistribution to selectively activate the inactive light emitting diodesas needed, to maintain the desired color distribution in the integratedradiant energy. The color sensor measures the color of the integratedradiant energy produced by the system and provides a color measurementsignal to the microcontroller 129. If using the TAOS, Inc. color sensor,for example, the signal is a digital signal derived from a color tofrequency conversion.

The temperature sensor 147 may be a simple thermoelectric transducerwith an associated analog to digital converter, or a variety of othertemperature detectors may be used. The temperature sensor is positionedon or inside of the fixture, typically at a point that is near the LEDsources that produce most of the system heat. The temperature sensor 147provides a signal representing the measured temperature to themicrocontroller 129. The system logic, here implemented by themicrocontroller 129, can adjust intensity of one or more of the LEDs inresponse to the sensed temperature, e.g. to reduce intensity of thesource outputs to compensate for temperature increases. The program ofthe microcontroller 129, however, would typically manipulate theintensities of the various LEDs so as to maintain the desired colorbalance between the various wavelengths of light used in the system,even though it may vary the overall intensity with temperature. Forexample, if temperature is increasing due to increased drive current tothe active LEDs (with increased age or heat), the controller maydeactivate one or more of those LEDs and activate a corresponding numberof the sleepers, since the newly activated sleeper(s) will providesimilar output in response to lower current and thus produce less heat.

The above discussion of FIG. 10 related to programmed digitalimplementations of the control logic. Those skilled in the art willrecognize that the control also may be implemented using analogcircuitry. FIG. 11 is a circuit diagram of a simple analog control for alighting apparatus (e.g. of the type shown in FIG. 1) using Red, Greenand Blue LEDs. The user establishes the levels of intensity for eachtype of radiant energy emission (Red, Green or Blue) by operating acorresponding one of the potentiometers. The circuitry essentiallycomprises driver circuits for supplying adjustable power to two or threesets of LEDs (Red, Green and Blue) and analog logic circuitry foradjusting the output of each driver circuit in accord with the settingof a corresponding potentiometer. Additional potentiometers andassociated circuits would be provided for additional colors of LEDs.Those skilled in the art should be able to implement the illustratedanalog driver and control logic of FIG. 11 without further discussion.

The systems described above have a wide range of applications, wherethere is a desire to set or adjust color provided by a lighting fixture.These include task lighting applications, signal light applications, aswells as applications for illuminating an object or person. Somelighting applications involve a common overall control strategy for anumber of the systems. As noted in the discussion of FIG. 10, thecontrol circuitry may include a communication interface 139 or 141allowing the microcontroller 129 to communicate with another processingsystem. FIG. 12 illustrates an example in which control circuits 21 of anumber of the radiant energy generation systems with the lightintegrating and distribution type fixture communicate with a mastercontrol unit 151 via a communication network 153. The master controlunit 151 typically is a programmable computer with an appropriate userinterface, such as a personal computer or the like. The communicationnetwork 153 may be a LAN or a wide area network, of any desired type.The communications allow an operator to control the color and outputintensity of all of the linked systems, for example to provide combinedlighting effects.

The commonly controlled lighting systems may be arranged in a variety ofdifferent ways, depending on the intended use of the systems. FIG. 13for example, shows a somewhat random arrangement of lighting systems.The circles represent the output openings of those systems, such as thelarge opening of the system deflectors. The dotted lines represent thefields of the emitted radiant energy. Such an arrangement of lightingsystems might be used to throw desired lighting on a wall or otherobject and may allow the user to produce special lighting effects atdifferent times. Another application might involve providing differentcolor lighting for different speakers during a television program, forexample, on a news program, panel discussion or talk show.

The commonly controlled radiant energy emission systems also may bearranged in a two-dimensional array or matrix. FIG. 14 shows an exampleof such an array. Again, circles represent the output openings of thosesystems. In this example of an array, the outputs are tightly packed.Each output may serve as a color pixel of a large display system.Dynamic control of the outputs therefore can provide a video displayscreen, of the type used as “Jumbo-Trons” in stadiums or the like.

While the foregoing has described what are considered to be the bestmode and/or other examples, it is understood that various modificationsmay be made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that they may be appliedin numerous applications, only some of which have been described herein.It is intended by the following claims to claim any and allmodifications and variations that fall within the true scope of thepresent concepts.

1. An apparatus for emitting radiant energy, comprising: an integratingcavity, having a diffusely reflective interior surface and an aperturefor allowing emission of combined radiant energy; a plurality of sourcesof radiant energy coupled to supply radiant energy into the interior ofthe integrating cavity; wherein each of the sources emits radiant energyof a different wavelength, and the combined radiant energy emittedthrough the aperture includes radiant energy of the differentwavelengths; control circuitry coupled to the sources for establishingoutput intensity of radiant energy of each of the sources to set aspectral characteristic of the combined radiant energy emitted throughthe aperture; and a deflector having a reflective inner surface coupledto the aperture to deflect at least some of the combined radiant energy.2. The apparatus of claim 1, wherein the deflector comprises a conicaldeflector comprising: a small opening at a proximal end of the conicaldeflector, coupled to the aperture of the integrating cavity; a largeropening at a distal end of the conical deflector; and a specularinterior surface between the distal end and the proximal end.
 3. Theapparatus of claim 1, wherein at least a substantial portion of thereflective interior surface of the deflector exhibits specularreflectivity with respect to the combined radiant energy.
 4. Theapparatus of claim 1, wherein the plurality of sources comprises: one ormore light emitting diodes for emitting light of a first color; and oneor more light emitting diodes for emitting light of a second color,wherein the second color is different from the first color.
 5. Theapparatus of claim 4, wherein the plurality of sources further comprisesone or more light emitting diodes for emitting light of a third colordifferent from the first and second colors.
 6. The apparatus of claim 5,wherein the first, second and third colors are red, green and blue,respectively.
 7. The apparatus of claim 5, wherein the plurality ofsources further comprises one or more light emitting diodes for emittinglight of a fourth color different from the first, second and thirdcolors.
 8. The apparatus of claim 1, wherein: the apparatus furthercomprises a temperature sensor, and the control circuitry is alsoresponsive to the sensed temperature.
 9. The apparatus of claim 1,wherein the control circuitry comprises means for manually defining adesired color distribution.
 10. The apparatus of claim 1, wherein thecontrol circuitry comprises a data interface for receiving data defininga desired color distribution.
 11. The apparatus of claim 1, wherein thecontrol circuitry comprises means for pre-setting the desired colordistribution.
 12. The apparatus of claim 1, wherein the integratingcavity is formed of a diffusely reflective plastic material.
 13. Theapparatus of claim 12, wherein the diffusely reflective plastic materialis a molded plastic, comprising polypropylene and having a 98%reflectivity.
 14. The apparatus of claim 1, wherein the integratingcavity comprises a rigid substrate having an interior surface, and adiffusely reflective coating layer formed on the interior surface of thesubstrate so as to provide the diffusely reflective interior surface ofthe integrating cavity.
 15. The apparatus of claim 1, wherein thediffusely reflective interior surface of the integrating cavity has ashape corresponding to a substantial portion of a sphere.
 16. Theapparatus of claim 15, wherein the shape corresponds to a hemisphere.17. The apparatus of claim 1, wherein the integrating cavity comprises abase, a mask separated from the base, and a cavity formed in at leastone of the base and the mask, wherein: opposing surfaces of the base andmask exhibit a diffuse reflectivity, and the mask is sized andpositioned relative to the base so as to constructively occlude anactive region of the base.
 18. The apparatus of claim 1, wherein thediffusely reflective interior surface of the integrating cavity has ashape at least a portion of which corresponds to a substantial portionof a cylinder.
 19. An apparatus for emitting radiant energy, comprising:an integrating cavity, having a diffusely reflective interior surfaceand an aperture for allowing emission of combined radiant energy; aplurality of sources of radiant energy coupled to supply radiant energyinto the interior of the integrating cavity, each of the sourcesemitting radiant energy of a different wavelength, and the combinedradiant energy emitted through the aperture including radiant energy ofthe different wavelengths; and control circuitry coupled to the sourcesfor establishing output intensity of radiant energy of each of thesources to set a spectral characteristic of the combined radiant energyemitted through the aperture, wherein: the plurality of sourcescomprises one or more first color light emitting diodes for emittinglight of a first color and one or more second color light emittingdiodes for emitting light of a second color, wherein the second color isdifferent from the first color; and the one or more first color lightemitting diodes comprise an initially active light emitting diode foremitting light of the first color and an initially inactive lightemitting diode for emitting light of the first color on an as neededbasis; and the one or more second color light emitting diodes comprisean initially active light emitting diode for emitting light of thesecond color and an initially inactive light emitting diode for emittinglight of the second color on an as needed basis.
 20. An apparatus foremitting radiant energy, comprising: an integrating cavity, having adiffusely reflective interior surface and an aperture for allowingemission of combined radiant energy; a plurality of sources of radiantenergy coupled to supply radiant energy into the interior of theintegrating cavity, wherein: each of the sources emits radiant energy ofa different wavelength, and the combined radiant energy emitted throughthe aperture includes radiant energy of the different wavelengths; andthe plurality of sources comprises one or more light emitting diodes foremitting light of a first color and one or more light emitting diodesfor emitting light of a second color, the second color being differentfrom the first color; and control circuitry coupled to the sources forestablishing output intensity of radiant energy of each of the sourcesto set a spectral characteristic of the combined radiant energy emittedthrough the aperture, wherein the control circuitry comprises: a colorsensor responsive to the combined radiant energy; and logic circuitryresponsive to color detected by the sensor to control output intensityof the one or more first color light emitting diodes and intensity ofthe one or more second color light emitting diodes, so as to provide adesired color distribution in the combined radiant energy.
 21. Theapparatus of claim 20, wherein: the one or more first color lightemitting diodes comprise an initially active light emitting diode foremitting light of the first color and an initially inactive diode foremitting light of the first color on an as needed basis; and the one ormore second color light emitting diodes comprise an initially activelight emitting diode for emitting light of the second color and aninitially inactive diode for emitting light of the second color on an asneeded basis.
 22. The apparatus of claim 21, wherein the logic circuitryis responsive to the detected color to selectively activate the inactivelight emitting diodes, as needed to maintain the desired colordistribution in the integrated radiant energy.
 23. The apparatus ofclaim 21, wherein: the apparatus further comprises a temperature sensor,and the control circuitry selectively activates the inactive lightemitting diodes as needed, in response to sensed variations intemperature.
 24. An apparatus for emitting radiant energy, comprising:an integrating cavity, having a diffusely reflective interior surfaceand an aperture for allowing emission of combined radiant energy; aplurality of sources of radiant energy coupled to supply radiant energyinto the interior of the integrating cavity; wherein each of the sourcesemits radiant energy of a different wavelength, and the combined radiantenergy through the aperture includes radiant energy of the differentwavelengths; and control circuitry coupled to the sources forestablishing output intensity of radiant energy of each of the sourcesto set a spectral characteristic of the combined radiant energy emittedthrough the aperture, wherein intensity of the combined radiant energyemitted through the aperture is of a level for use in a luminationapplication.
 25. An apparatus for emitting radiant energy, comprising:an integrating cavity, having a diffusely reflective interior surfaceand an aperture for allowing emission of combined radiant energy; aplurality of sources of radiant energy coupled to supply radiant energyinto the interior of the integrating cavity; wherein each of the sourcesemits radiant energy of a different wavelength, and the combined radiantenergy emitted through the aperture includes radiant energy of thedifferent wavelengths; and control circuitry coupled to the sources forestablishing output intensity of radiant energy of each of the sourcesto set a spectral characteristic of the combined radiant energy emittedthrough the aperture, wherein intensity of the combined radiant energyemitted through the aperture is of a level sufficient for task lighting.26. An apparatus for emitting radiant energy, comprising: an integratingcavity, having a diffusely reflective interior surface and an aperturefor allowing emission of combined radiant energy; a plurality of sourcesof radiant energy coupled to supply radiant energy into the interior ofthe integrating cavity; wherein each of the sources emits radiant energyof a different wavelength, and the combined radiant energy emittedthrough the aperture includes radiant energy of the differentwavelengths; and control circuitry coupled to the sources forestablishing output intensity of radiant energy of each of the sourcesto set a spectral characteristic of the combined radiant energy emittedthrough the aperture, wherein the cavity has a plurality of openings atpoints on the interior of the cavity, and the plurality of sources arepositioned to emit radiant energy directly into the interior of theintegrating cavity through respective ones of the openings.
 27. Anapparatus for emitting radiant energy, comprising: an integratingcavity, having a diffusely reflective interior surface and an aperturefor allowing emission of combined radiant energy; a plurality of sourcesof radiant energy coupled to supply radiant energy into the interior ofthe integrating cavity; wherein each of the sources emits radiant energyof a different wavelength, and the combined radiant energy emittedthrough the aperture includes radiant energy of the differentwavelengths: and control circuitry coupled to the sources forestablishing output intensity of radiant energy of each of the sourcesto set a spectral characteristic of the combined radiant energy emittedthrough the aperture, and a plurality of optical fibers coupled betweenthe sources and the integrating cavity to supply radiant energy from thesources to the interior of the cavity.
 28. An apparatus for emittingradiant energy, comprising: an integrating cavity, having a diffuselyreflective interior surface and an aperture for allowing emission ofcombined radiant energy; a plurality of sources of radiant energycoupled to supply radiant energy into the interior of the integratingcavity, wherein: each of the sources emits radiant energy of a differentwavelength, the combined radiant energy emitted through the apertureincludes radiant energy of the different wavelengths, radiant energyfrom the sources enters the cavity at points on the interior surface ofthe integrating cavity, and the points are not directly visible throughthe aperture; and control circuitry coupled to the sources forestablishing output intensity of radiant energy of each of the sourcesto set a spectral characteristic of the combined radiant energy emittedthrough the aperture.
 29. The apparatus of claim 28, wherein intensityof the combined radiant energy emitted through the aperture is of alevel for use in a lumination application.
 30. The apparatus of claim28, wherein intensity of the combined radiant energy emitted through theaperture is of a level sufficient for task lighting.
 31. The apparatusof claim 28, wherein the cavity has a plurality of openings at points onthe interior of the cavity, and the plurality of sources are positionedto emit radiant energy directly into the interior of the integratingcavity through respective ones of the openings.
 32. A system comprising:a plurality of apparatuses for emitting radiant energy, each apparatuscomprising: a) an integrating cavity, having a diffusely reflectiveinterior surface and an aperture for allowing emission of combinedradiant energy; b) a plurality of sources of radiant energy coupled tosupply radiant energy into the interior of the integrating cavity; c)wherein each of the sources emits radiant energy of a differentwavelength, and the combined radiant energy emitted through the apertureincludes radiant energy of the different wavelengths; d) controlcircuitry coupled to the sources for establishing output intensity ofradiant energy of each of the sources to set a spectral characteristicof the combined radiant energy emitted through the aperture; and amaster controller coupled to the control circuitry of each of theapparatuses, for providing a common control of all radiant energyemissions by the apparatuses.
 33. The system as in claim 32, wherein theplurality of apparatus are arranged side by side in a two-dimensionalarray.
 34. An apparatus for emitting radiant energy of multiplewavelengths comprising: a plurality of first light emitting diodes(LEDs) for emitting radiant energy of a first wavelength, at least oneof the first LEDs being initially active and at least one other of thefirst LEDs being initially inactive; a plurality of second LEDs foremitting radiant energy of a second wavelength different from the firstwavelength, at least one of the second LEDs being initially active andat least one of the second LEDs being initially inactive; a controllercoupled to control operation of the first and second LEDs; and a sensorarranged to sense at least one condition relating to operation of theapparatus, wherein the controller selectively activates one or more ofthe inactive LEDs in response to the condition sensed by the sensor. 35.The apparatus as in claim 34, wherein the sensor comprises a colordetector responsive to combined output from the first and second LEDs.36. The apparatus of claim 34, wherein the sensor comprises atemperature detector.
 37. The apparatus of claim 34, further comprisingan integrating cavity for receiving and combining energy from the firstand second LEDs, the cavity having an aperture through which theapparatus emits combined radiant energy of the multiple wavelengths. 38.An apparatus for emitting light, comprising: an integrating cavity,having a diffusely reflective interior surface and an aperture forallowing emission of combined light; a plurality of sources of lightcoupled to supply light into the interior of the integrating cavity, theplurality of sources comprising one or more first color light emittingdiodes for emitting light of a first color and one or more second colorlight emitting diodes for emitting light of a second color differentfrom the first color, such that combined light emitted through theaperture includes light of the different first and second colors; andcontrol circuitry coupled to the sources for establishing outputintensity of light of each of the sources to set a spectralcharacteristic of the combined light emitted through the aperture,wherein: the one or more first color light emitting diodes comprise aninitially active light emitting diode for emitting light of the firstcolor and an initially inactive light emitting diode for emitting lightof the first color on an as needed basis; and the one or more secondcolor light emitting diodes comprise an initially active light emittingdiode for emitting light of the second color and an initially inactivelight emitting diode for emitting light of the second color on an asneeded basis.
 39. The apparatus of claim 38, wherein intensity of thecombined light emitted through the aperture is of a level for use in alumination application.
 40. The apparatus of claim 38, wherein intensityof the combined light emitted through the aperture is of a levelsufficient for task lighting.
 41. The apparatus of claim 38, wherein thecavity has a plurality of openings at points on the interior of thecavity, and the light emitting diodes are positioned to emit lightdirectly into the interior of the integrating cavity through respectiveones of the openings.
 42. The apparatus of claim 38, wherein light fromthe sources enters the cavity at points on the interior surface of theintegrating cavity, and the points are not directly visible through theaperture.
 43. An apparatus for emitting light, comprising: anintegrating cavity, having a diffusely reflective interior surface andan aperture for allowing emission of combined light; a plurality ofsources of light coupled to supply light into the interior of theintegrating cavity, the plurality of sources comprising one or morefirst color light emitting diodes for emitting light of a first colorand one or more second color light emitting diodes for emitting light ofa second color different from the first color , such that combined lightemitted through the aperture includes light of the different first andsecond colors; and control circuitry coupled to the sources forestablishing output intensity of light of each of the sources to set aspectral characteristic of the combined light emitted through theaperture, wherein the control circuitry comprises: a color sensorresponsive to the combined light; and logic circuitry responsive tocolor detected by the sensor to control output intensity of the one ormore first color light emitting diodes and intensity of the one or moresecond color light emitting diodes, so as to provide a desired colordistribution in the combined light.
 44. The apparatus of claim 43,wherein intensity of the combined light emitted through the aperture isof a level for use in a lumination application.
 45. The apparatus ofclaim 43, wherein intensity of the combined light emitted through theaperture is of a level sufficient for task lighting.
 46. The apparatusof claim 43, wherein the cavity has a plurality of openings at points onthe interior of the cavity, and the plurality of sources are positionedto emit light directly into the interior of the integrating cavitythrough respective ones of the openings.
 47. The apparatus of claim 43,wherein light from the sources enters the cavity at points on theinterior surface of the integrating cavity, and the points are notdirectly visible through the aperture.
 48. An apparatus for emittinglight, comprising: an integrating cavity, having a diffusely reflectiveinterior surface and an aperture for allowing emission of combinedlight; one or more light emitting diodes for emitting light of a firstcolor into the interior of the integrating cavity; one or more lightemitting diodes for emitting light of a second color into the interiorof the integrating cavity, the second color being different from thefirst color; wherein the combined light emitted through the apertureincludes light of the first and second colors; control circuitry coupledto the light emitting diodes for establishing output intensity of lightof each of the light emitting diodes to set a spectral characteristic ofthe combined light emitted through the aperture; and a deflector havinga reflective inner surface coupled to the aperture to deflect at leastsome of the combined light.
 49. The apparatus of claim 48, wherein thedeflector comprises a conical deflector comprising: a small opening at aproximal end of the conical deflector, coupled to the aperture of theintegrating cavity; a larger opening at a distal end of the conicaldeflector; and a specular interior surface between the distal end andthe proximal end.
 50. The apparatus of claim 48, wherein at least asubstantial portion of the reflective interior surface of the deflectorexhibits specular reflectivity with respect to the combined light. 51.The apparatus of claim 48, further comprising one or more light emittingdiodes for emitting light of a third color different from the first andsecond colors.
 52. The apparatus of claim 51, wherein the first, secondand third colors are red, green and blue, respectively.
 53. Theapparatus of claim 51, further comprising one or more light emittingdiodes for emitting light of a fourth color different from the first,second and third colors.
 54. An apparatus for emitting light,comprising: an integrating cavity, having a diffusely reflectiveinterior surface and an aperture for allowing emission of combinedlight; a light emitting diode for emitting light of a first color intothe interior of the integrating cavity at a point on the interiorsurface of the integrating cavity not directly visible through theaperture; a light emitting diode for emitting light of a second colorinto the interior of the integrating cavity at a point on the interiorsurface of the integrating cavity not directly visible through theaperture, the second color being different from the first color; whereinthe combined light emitted through the aperture includes light of thefirst and second colors; and control circuitry coupled to the lightemitting diodes for establishing output intensity of light of each ofthe light emitting diodes to set a spectral characteristic of thecombined light emitted through the aperture.